The invention relates to a packaging machine for delicate rod-shaped objects, especially cigarettes or the like, comprising at least one wheel for carrying, along a path between many operating units or stations, a series of ordered groups of cigarettes, which wheel is provided with one or more peripheral sockets, each designed to accommodate one ordered group of cigarettes and each being open on the peripheral side of the wheel and/or on at least one face of said wheel.
At present, especially in cigarette packaging machines, wheels with sockets are used for forming the inner foil wrapping and the packet, which may be soft or hard. The packets are formed by folding the foil wrapping, or the wrapping for the soft pack or the preformed blank for the hard pack, around the corresponding ordered group of cigarettes. The wrappers and blanks are folded by stationary folding means and movable folding means distributed in predetermined positions for each folding step around the periphery of a wheel which is mounted so as to rotate, in predetermined steps, about its axis and which accommodates the ordered groups of cigarettes in corresponding sockets complementary in shape to the cross section of the ordered group of cigarettes.
In order for packaging machines to achieve high productivity, the forming wheels have to rotate at very high speeds. The advancing steps must therefore be performed extremely quickly, which makes for real problems of inertia because of the continual accelerations and decelerations. It is advantageous, therefore, for the forming wheels to be constructed with extremely low mass.
In addition, since many different shapes of cigarette packets exist, it is also necessary to make the sockets of the forming wheels easily adaptable to the different dimensions of the ordered groups of cigarettes, without excessively complicating the construction, and increasing the weight, of the forming wheels.
The object of the invention is to provide a carrying wheel for packaging machines of the sort described at the outset whose construction is simple and inexpensive, as well as being very light and easily adaptable to the different shapes of packets, while at the same time guaranteeing the necessary robustness and mechanical strength.
The invention achieves the above objects in the form of a packaging machine of the sort described at the outset, in which the wheel or wheels for carrying the ordered groups of cigarettes consist of a central hub part, while around the peripheral sockets for accommodating the ordered groups of cigarettes said wheel is formed by annular rims attached removably to the periphery of the central hub, which rims are separated axially by a lesser distance than the dimension of the ordered group of cigarettes, in the axial direction of the wheel, and form the accommodating sockets by means of supporting cradles shaped to correspond with those parts of the ordered groups of cigarettes that coincide with said rims.
The ordered groups of cigarettes are preferably accommodated in the wheel with the axes of the cigarettes oriented approximately parallel with the axis of the wheel. If this arrangement is adopted, the socket parts of the annular rims will be shaped in such a way as to form cradles for accommodating the corresponding end parts of the ordered groups of cigarettes.
The annular rims may be made in the form of closed rings or divided into a plurality of separate segments forming, in combination with each other, an essentially continuous ring. Alternatively, the rims may be made up of a plurality of annular segments separated from each other and essentially extending only in the immediate vicinity of the sockets for accommodating the ordered groups of cigarettes.
The central hub is advantageously made of metallic material, such as light alloy and/or the like, whereas the annular rims or the annular segments which go to make these up are made of plastic material.
In an improvement, the annular rims, or the annular segments forming these, may comprise weight-reducing openings. Said weight-reducing openings are preferably produced in such a way as to form radial connecting ribs between the outer peripheral part and the inner peripheral part of the annular rims and/or of the segments forming these.
Another feature is that the supporting cradles forming the sockets for accommodating the ordered groups of cigarettes are formed by axial flanges or thickenings complementary in shape to the ordered group of cigarettes, these flanges or thickenings being situated on the opposing annular rims in axial alignment with each other. If an aperture is provided on the corresponding face of the wheel, the flanges and/or thickenings run around the edge of said aperture in the corresponding annular rim. If there is no aperture on the face of the wheel, the thickenings or flanges are made in the form of ribs of appropriate shape projecting axially from the inner face of the corresponding annular rim.
In particular, the sockets of the wheel according to the invention are open on both faces of the wheel and around the latter's periphery. If this arrangement is adopted, the annular rims comprise, in axially coinciding positions, recesses complementary in shape to the cross section of the group of cigarettes, said recesses being open around the outer periphery of said rims and the flanges or thickenings being situated around the edges of said recesses.
The recesses or cradles are of different shapes according to the different shapes of the packets and hence of the ordered groups of cigarettes. Advantageously, for easy adaptation of the forming wheel to the packet, different types of annular rims are provided, all having the same internal diameter and the same external diameter, the difference between the internal and the external diameters being determined by the shape of whichever socket is radially the longest.
The advantages of the invention will be clear from the above account. The composite structure of the forming wheels enables both its cost of manufacture and its inertial mass to be greatly reduced. It also permits easy and rapid adaptation of the packaging machine to the different shapes of packet envisaged. Moreover, these advantages are achieved in a simple and inexpensive construction which still meets the requisite characteristics of mechanical strength.